In general, surface-coated cutting tools include indexable inserts which are detachably attached to a tip portion of an insert holder in turning or planning of work materials such as various kinds of steel or cast iron, drills or miniature drills which are used in drilling or the like of the work materials, and solid end mills which are used in face milling, grooving, shoulder milling, or the like of the work materials. In addition, throw away end mill tools or the like have been known which include the indexable insert detachably attached thereto and perform cutting in the same manner as the solid end mills.
In addition, as a coated tool, coated tools in which the surface of a body made of tungsten carbide (hereinafter, represented by WC)-based cemented carbide, titanium carbonitride (hereinafter, represented by TiCN)-based cermet, or a cubic boron nitride sintered material (hereinafter, represented by cBN) (hereinafter, collectively referred to as a tool body) is coated with a complex nitride layer of Cr and Al ((Cr, Al)N) or a complex nitride layer of Ti and Al ((Ti, Al)N) as a hard coating layer through an arc ion plating method have been known.
In addition, many proposals have been made in order to improve the cutting performance of the coated tool.
For example, in Japanese Unexamined Publication No. 2008-188734, it is proposed that a hard coating layer formed of a (Cr, Al)N layer, which has biaxial crystal orientation and is formed of a complex nitride layer of Cr and Al satisfying a composition formula (Cr1-xAlx)N (x is 0.40 to 0.70 in terms of atomic ratio), and in which in a case where crystal orientation analysis by EBSD is carried out in regard to the complex nitride layer, an area ratio of crystal grains having crystal orientation <100> within a range of 0 to 15 degrees from a normal direction of a surface polishing face is 50% or more, and an area ratio of crystal grains having crystal orientation <100> within a range of 15 degrees around a maximum peak existing within a range of 0 to 54 degrees with respect to an optional direction orthogonal to a normal line of the surface polishing face is 50% or more, is formed on a surface of a tool body, and thus the fracture resistance of the hard coating layer in heavy cutting is improved.
In Japanese Unexamined Publication No. 2010-12564, it is proposed that a hard coating layer 1 is coated on the surface side, a hard coating layer 2 is coated on the tool body side, the hard coating layer 1 is (Cr1-aAla)Nx, where 0.5≤a≤0.75 and 0.9≤x≤1.1, the hard coating layer 2 is (TibAl1-bb)Ny, where 0.4≤b≤0.6 and 0.9≤y≤1.1, in a case where the lattice constant of the (200) plane of the hard coating layer 1 by X-ray diffraction is α1 (nm), 0.411≤α1≤0.415, and in a case where the lattice constant of the (200) plane of the hard coating layer 2 is α2 (nm), 0.413≤α2≤0.418, so that high hardness is maintained and a reduction in the residual compression stress is achieved, and moreover, the adhesion strength between the hard coating layers 1 and 2 is increased to increase the service life of the tool of a coated tool.
In Japanese Unexamined Publication No. H8-119774 and Japanese Patent No. 4191663, it is proposed that on a body formed of a cBN sintered material containing 20 vol % or more of cubic boron nitride, a hard heat-resistant film having a composition represented by (Ti1-xAlx)N (here, 0.3≤x≤0.7) is provided at a place related to at least cutting to improve the strength and the wear resistance as a cutting tool.
In Japanese Unexamined Publication No. 2009-101491, it is proposed that in a case where a lower layer formed of a (Ti, Al)-based complex nitride or complex carbonitride layer and an upper layer formed of a (Cr, Al)-based complex nitride layer are coated on a surface of a tool body made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, and the upper layer is configured to have an alternate laminated structure of a thin layer A having a cubic structure and a thin layer B in which a cubic structure and a hexagonal structure are mixed, the lubricity and the wear resistance in high-speed strong intermittent cutting are improved.
Japanese Unexamined Publication No. 2009-101491 describes that in a case where the lower layer is represented by a composition formula (Ti1-Q-RAlQM1R)(C, N), the lower layer is a complex nitride or complex carbonitride layer of Ti, Al, and M1 satisfying 0.4≤Q≤0.65 and 0≤R≤0.1 (Q represents a content ratio of Al in terms of atomic ratio, R represents a total content ratio of the component M1 in terms of atomic ratio, and the component M1 represents one or more elements selected from Si, B, Zr, Y, V, W, Nb, and Mo.), in a case where the thin layer A is represented by a composition formula (Cr1-α-βAlαM2β)N, the thin layer A is a complex nitride layer of Cr, Al, and M2 having a cubic structure satisfying 0.25≤α≤0.65 and 0<β≤0.1 (α represents a content ratio of Al in terms of atomic ratio, β represents a total content ratio of the component M2 in terms of atomic ratio, and the component M2 represents one or more elements selected from Zr, Y, V, W, Nb, Mo, and Ti.), and in a case where the thin layer B is represented by a composition formula (Cr1-γ-δAlγM3δ)N, the thin layer B is a complex nitride layer of Cr, Al, and M3 satisfying 0.75≤γ≤0.95 and 0<δ≤0.1 (γ represents a content ratio of Al in terms of atomic ratio, δ represents a total content ratio of the component M3 in terms of atomic ratio, and the component M3 represents one or more elements selected from Zr, Y, V, W, Nb, Mo, and Ti.).